Light and light sensor

ABSTRACT

An LED-based light tube for use in a conventional fluorescent fixture includes a housing including a light transmitting portion, at least one electrical connector attached to the housing and configured for engagement with the conventional fluorescent fixture, at least one LED arranged to produce light in a direction toward the light transmitting portion, a sensor operable to detect a brightness level and output a signal corresponding to the detected brightness level, and a controller in electrical communication with the at least one electrical connector, operable to: compare the signal to a predetermined value corresponding to a desired brightness level and control an amount of power provided to the at least one LED in response to the signal to adjust the light produced by the at least one LED to achieve the desired brightness level.

STATEMENT OF RELATED CASES

This application is a continuation of U.S. patent application Ser. No.12/572,471, filed Oct. 2, 2009, which claims priority from U.S.Provisional Patent Application Ser. No. 61/108,354 filed Oct. 24, 2008.

FIELD

An LED-based light as described herein relates to “smart buildings” thatcan automatically control lighting in response to various environmentalconditions.

BACKGROUND

Lights in buildings are generally controlled by switches, such aswall-mounted switches in the vicinity of one or more lights. The switchcan include a dimmer for varying the brightness of one or more lights.However, lights are often left on when not needed, such as when nopeople are around the lights or when sources of light besides the lights(e.g., sunlight passing through windows and/or skylights) providesufficient illumination.

SUMMARY

Known smart buildings that can automatically control variousenvironmental characteristics, such as a lighting brightness level, ofone or more rooms of a building are typically expensive to manufactureand install. For example, known smart building components typically arenot compatible with standard building fixtures, such as conventionalfluorescent tube fixtures, and thus can require an electrician toinstall.

Embodiments of LED-based lights described herein can be used totransform a building with standard fixtures, such as standardfluorescent tube fixtures, into a smart building. Many advantages areoffered by the LED-based lights described herein, such as allowing for alow-cost smart building and automatically providing an alert when anefficiency of the LED-based light becomes too low.

In one embodiment, an LED-based light tube for use in a conventionalfluorescent fixture includes a housing including a light transmittingportion and at least one electrical connector attached to the housingand configured for engagement with the conventional fluorescent fixture.The LED-based light tube also includes at least one LED arranged toproduce light in a direction toward the light transmitting portion and asensor operable to detect a brightness level and output a signalcorresponding to the detected brightness level. Further, the LED-basedlight tube includes a controller in electrical communication with the atleast one electrical connector and operable to: compare the signal to apredetermined value corresponding to a desired brightness level andcontrol an amount of power provided to the at least one LED in responseto the signal to adjust the light produced by the at least one LED toachieve the desired brightness level.

In another embodiment, a system for measuring the efficiency of a lightincludes an LED-based light including at least one electrical connectorcompatible with a standardized light fixture, at least one LED, and acontroller in electrical communication with the at least one electricalconnector and operable to control the at least one LED. The system alsoincludes a sensor in communication with the controller and operable todetect a brightness level. The controller is operable to estimate anefficiency of the at least one LED at least partially based on thebrightness level detected by the sensor.

In another embodiment, an LED-based light for use in a conventionalfixture includes a housing including a light transmitting portion, atleast one electrical connector attached to the housing and configuredfor engagement with the conventional fixture and at least one LEDarranged to produce light in a direction toward the light transmittingportion. The LED-based light also includes means for transmitting asignal corresponding to lighting information of the LED-based light. Thetransmitted signal is usable by a remote controller to control apredetermined function separate from the LED-based light.

These and other embodiments will be described in additional detailhereafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example of an LED light tube;

FIG. 2 is a schematic perspective view of a smart building system;

FIG. 3 is a schematic perspective view of yet another example of an LEDlight tube; and

FIG. 4 is a flowchart illustrating operation of an example of an LEDlight tube.

DESCRIPTION

FIGS. 1-4 are discussed in reference to a light and a light sensor. Asshown in FIG. 1, a light fixture 14 can accept an LED-based light 16.The light fixture 14 can be designed to accept standard fluorescenttubes, such as a T-5, T-8, or T-12 fluorescent tube, or other standardsized light, such as incandescent bulbs. Alternatively, the fixture 14can be designed to accept non-standard sized lights, such as lightsinstalled by an electrician.

The LED light tube 16 can include a housing 22, a circuit board 24, LEDs26, a pair of end caps 28, a controller 25, and a receiver 27 as shownin FIG. 1. The housing 22 as shown in FIG. 1 is a light transmittingcylindrical tube. The housing 22 can be made from polycarbonate,acrylic, glass or another light transmitting material (i.e., the housing22 can be transparent or translucent). For example, a translucenthousing 22 can be made from a composite, such as polycarbonate withparticles of a light refracting material interspersed in thepolycarbonate. While the illustrated housing 22 is cylindrical, housingshaving a square, triangular, polygonal, or other cross sectional shapecan alternatively be used. Similarly, while the illustrated housing 22is linear, housings having an alternative shape, e.g., a U-shape or acircular shape can alternatively be used. Additionally, the housing 22need not be a single piece as shown in FIG. 1. Instead, another exampleof a housing can be formed by attaching multiple individual parts, notall of which need be light transmitting. For example, such a housing caninclude an opaque lower portion and a lens or other transparent coverattached to the lower portion to cover the LEDs 26. The housing 22 canbe manufactured to include light diffusing or refracting properties,such as by surface roughening or applying a diffusing film to thehousing 22. For compatibility with the fixture 14 as discussed above,the housing 22 can have a length such that the light 16 is approximately48″ long, and the housing 22 can have a 0.625″, 1.0″, or 1.5″ diameter.

The circuit board 24 as illustrated in FIG. 1 is an elongate printedcircuit board. Multiple circuit board sections can be joined by bridgeconnectors to create the circuit board 24. The circuit board 24 as shownin FIG. 1 is slidably engaged with the housing 22, though the circuitboard 24 can alternatively be clipped, adhered, snap- or friction-fit,screwed or otherwise connected to the housing 22. For example, thecircuit board 24 can be mounted on a heat sink that is attached to thehousing 22. Also, other types of circuit boards may be used, such as ametal core circuit board. Or, instead of a circuit board 24, other typesof electrical connections (e.g., wires) can be used to electricallyconnect the LEDs 26 to a power source.

The light 16 can include two bi-pin end caps 28 (i.e., each end cap 28can carry two pins), one at each longitudinal end of the housing 22, forphysically and electrically connecting the light 16 to the fixture 14.The end caps 28 can be the sole physical connection between the light 16and the fixture 14. The end caps 28 can be electrically connected to thecircuit board 24 to provide power to the LEDs 26. Each end cap 28 caninclude two pins, though two of the total four pins can be “dummy pins”that do not provide an electrical connection. Alternatively, other typesof electrical connectors can be used, such as an end cap carrying asingle pin. Also, while the end caps 28 are shown as includingcup-shaped bodies, the end caps 28 can have a different configuration(e.g., the end caps 28 can be shaped to be press fit into the housing22). One or both of the end caps 28 can additionally include electriccomponents, such as a rectifier and filter.

The LEDs 26 can be surface-mount devices of a type available fromNichia, though other types of LEDs can alternatively be used. Forexample, although surface-mounted LEDs 26 are shown, one or more organicLEDs can be used in place of or in addition thereto. The LEDs 26 can bemounted to the circuit board 24 by solder, a snap-fit connection, orother means. The LEDs 26 can produce white light. However, LEDs thatproduce blue light, ultra-violet light or other wavelengths of light canbe used in place of white light emitting LEDs 26.

The number of LEDs 26 can be a function of the desired power of thelight 16 and the power of the LEDs 26. For a 48″ light, such as thelight 16, the number of LEDs 26 can vary from about five to four hundredsuch that the light 16 outputs approximately 500 to 3,000 lumens.However, a different number of LEDs 26 can alternatively be used, andthe light 16 can output a different amount of lumens. The LEDs 26 can beevenly spaced along the circuit board 24, and the spacing of the LEDs 26can be determined based on, for example, the light distribution of eachLED 26 and the number of LEDs 26.

The controller 25 can be mounted on the circuit board 24, and caninclude a memory and a CPU for executing a program stored on the memory.That is, the controller 26 can be include a microprocessor or otherdigital or analog circuit that performs the tasks described herein. Thecontroller 25 can be in communication with the LEDs 26, the end caps 28,and the receiver 27 via the circuit board 24, though the controller 25can alternatively be in communication with the LEDs 26, end caps 28,and/or receiver 27 using wires or another connection. The controller 25can also be configured to regulate the amount of power provided to theLEDs 26. That is, the controller 28 can govern the amount of powerprovided from the end caps 28 to the LEDs 26. The controller 28 can bein communication with multiple subsets of LEDs 26 (such as individualLEDs 26) for providing a different amount of power to one or more of thesubsets of LEDs 26. Alternatively, a controller can be external of thelight 16. For example, a controller can be coupled to the fixture 14 tocontrol a light attached to the fixture 14.

The light 16 can additionally include a receiver 27 mounted on thecircuit board 24. The receiver 27 can be in communication with thecontroller 25 as mentioned above and with a remote transmitter as isdiscussed below in greater detail. For example, the receiver 27 can bein communication with the transmitter using a standard wireless protocol(e.g., a radio standard, a cellular standard such as 3G, Bluetooth, orWiFi). The receiver 27 can alternatively be in communication with thetransmitter in another manner such as hardwiring or via electric signalssent through the end caps 28. The receiver 27 can be configured toreceive signals from the transmitter, and the receiver 25 can transmitreceived signals to the controller 25.

While the light 16 is shown as being compatible with standard sizedfluorescent fixtures, an LED-based light having another shape, such asan incandescent bulb or another type of light, can alternatively beused. Also, other types of light sources, such as fluorescent orincandescent based light sources, can be used instead of the LEDs 26.

As illustrated in FIG. 2, the fixture 14 can be in a building 11including a light switch 31 and a light sensor 33, and the light 16 canbe installed in the fixture 14. The light switch 31 can control whetherpower is provided to the fixture 14. However, as is mentioned above anddescribed below in greater detail, the controller 25 can control whetherpower is provided to the LEDs 26, in which case the light switch 31 neednot be included. Also, if the building 11 is a “smart” building, thecontroller 25 and switch 31 can be in communication (e.g., via a wiredconnection, or via a wireless transmitter and a wireless receiver) suchthat the controller 25 can override the switch 31 to turn on the light16 even when the switch 31 is in an off position or vice versa.

The light sensor 33 can detect a level of light in an area of thebuilding 11 including the light 16, such as an amount of light thatstrikes the sensor 33. The light sensor 33 can include an integraltransmitter for transmitting a light level signal α to the receiver 27.The light sensor 33 can continuously transmit the signal, or the lightsensor 33 can include a controller (e.g., a controller including amemory and a CPU for executing a program stored on the memory) fordeciding when to transmit the signal. In addition to the light sensor33, other sensors can be in communication with the light 16. Forexample, the building 11 can also include a motion sensor, a sensor fordetermining whether a door is ajar, a sensor for determining when akeypad or other type of lock is actuated, a voice-activated sensor, aclock or calendar, a light sensor for measuring an amount of light inthe building 11 other than or including light provided by the light 16(e.g., an amount of sunlight entering the building 11), a power supplymonitor, and/or another type of sensor.

In operation, as shown by in FIG. 4, the light 16 produces light in stepS1. In step S2 the light sensor 33 can measure the amount of light thatstrikes the sensor 33, and the light sensor 33 can transmit the lightlevel signal α to the receiver 27 as shown in step S3. The receiver 27can communicate the light level signal α to the controller 25 as shownin step S4.

In step S5, the controller 25 can analyze the light level signal α. Forexample, the controller 25 can estimate a brightness of an area of thebuilding 11 including the light 16, the controller 25 can compare thelight level to a predetermined value (e.g., an amount of lightcomfortable for an ordinary person), or can analyze the light levelsignal α in some other manner. Depending on the light level signal α,the controller 25 can control the light 16 in various ways. For example,as shown in step S6, the controller 25 can adjust the brightness oflight produced by the LEDs 26. If the light level signal α indicates theamount of light detected is too high, the controller 25 can dim the LEDs26 or turn a subset of the LEDs 26 off. Alternatively, if the amount oflight is too low, the controller 25 can increase the brightness of theLEDs 26 or turn on a subset of the LEDs 26 that were previously off.Thus, the controller 25 can correct the amount of light provided by thelight 16 in response to changes in ambient light, such as if a level ofnatural light entering the area of the building 11 including the light16 increases or decreases, or if other lights are turned on or off.

In another example not illustrated, the light 16 can initially not beproducing light. The controller 25 can control the light 16 to beginproducing light in response to the light level signal α. For example,the light level signal α can indicate that the amount of light in anarea of the building 11 is below a predetermined level.

To avoid interference with the light sensor 33 by the light emitted bythe LEDs 26, the light sensor 33 can sense ambient light during a shortperiod, invisible to the eye, when the LEDs 26 are off. This short offperiod can occur due to line voltage zero-crossing, or a command fromthe controller 25.

Therefore, among other advantages, an occupant of the area of thebuilding 11 including the light 16 can avoid having to make an effort toturn on the light.

Returning to FIG. 3, as another example of operation of the light 16shown in step S7, the light level signal α can be analyzed by thecontroller 25 to determine an efficiency of the light 16. For example,the controller 25 can compare the amount of detected light with areference value, such as an amount of light detected at a previous dateif the light 16 includes a clock and/or calendar. The previous date canbe a date when conditions such as ambient light conditions were similar,such as a recent day at approximately the same time. The differencebetween the current amount of light being produced and the previousamount of light being produced can be used to calculate a change inefficiency of the light 16. The controller 25 can make this efficiencydetermination without turning the light 16 off, which can be beneficialif the light 16 is in a location such as a stairwell where a lack oflight can be dangerous. As an alternative efficiency test, thecontroller 25 can compare the amount of detected light when the light 16is on with an amount of light detected when the light 16 is off, withthe difference being used to calculate an amount of light produced bythe light 16.

The controller 25 can calculate the efficiency by comparing the amountof light produced by the light 16 with the reference value (e.g., anamount of light produced by the light 16 operating under idealconditions), or by comparing the amount of light produced by the light16 with the amount of power consumed by the light 16 (which can bemeasured with an ammeter and voltmeter, a wattmeter, or another powermeasuring device either integral with the light 16, electrically coupledto the fixture 14, or at another location).

As shown in step S8, the controller 25 can also determine whether thelight 16 should be replaced. For example, the controller 25 can comparethe efficiency of the light 16 with a predetermined value to determinewhether the light 16 should be replaced. The predetermined value can bea predetermined efficiency standard, such as the efficiency of the light16 when new, the efficiency of an ideal light, a maximal output of thelight 16, or some other value.

The controller 25 can also control the light 16 to indicate itsefficiency, which can provide notice that the light 16 should bereplaced. For example, the controller 25 can control the light 16 todisplay its efficiency using a digital read-out integral with the light16, a bar of light having a length equivalent with the efficiency, or inanother manner. Alternatively, the controller 25 can control the light16 to display when the efficiency of the light 16 is below apredetermined value, such as by illuminating at least one of the LEDs 26having a different color than surrounding LEDs 26, by causing at leastone of the LEDs 26 to flash, or by controlling the light 16 in someother manner. Once the efficiency of the light 16 drops below thepredetermined value, it can be understood that the light 16 should bereplaced. Thus, the light 16 can signal to a maintenance worker or otherpersonnel that the light 16 should be replaced.

Another light 40 as shown in FIG. 3 includes the housing 22, the circuitboard 24, the controller 25, the LEDs 26, and the end caps 28 similar tothe light 16. The light 40 can additionally include an integral lightlevel sensor 42 and a transmitter 44. The light sensor 42 can be mountedon the circuit board 24 to receive power via the end caps 28, and thelight sensor 42 can be in communication with the controller 25 and/orthe transmitter 44. The light level sensor 42 can protrude from thehousing 22 as shown in FIG. 3 or otherwise be positioned to sense anamount of light produced by at least some of the LEDs 26 (e.g., thesensor 42 can alternatively be contained within the housing 22, and oneor more reflectors can be included to direct a portion of light towardthe sensor 42). Alternatively, the light level sensor 42 can detect anamount of ambient light. The amount of ambient light can include lightproduced by the LEDs 26. The sensor 42 can communicate the light levelsignal α to the controller 25.

The transmitter 44 can be mounted on the circuit board 24 for receivingpower via the end caps 28. The transmitter 44 can be in communicationwith the controller 25 and/or the light sensor 24 for receiving thelight level signal α. The transmitter 44 can be configured to transmitthe light level signal α to a remote location, such as a smart buildingcontrol center or another smart building component.

With this configuration, the controller 25 in the light 40 can controlthe LEDs 26 and calculate an efficiency of the light based on the lightlevel signal α as discussed above in reference to the light 16. Thelight 40 can also indicate whether the light 40 should be replacedsimilar to as described above in reference to the light 16.Additionally, the inclusion of the transmitter 44 allows the light 40 toperform other functions. The transmitter 44 can transmit the light levelsignal α to the remote location, allowing the light level signal α to beused for controlling another component of a smart building (e.g., windowshades, another light, or some other component of a smart building) orfor another purpose. For example, the transmitter 44 can transmit anefficiency of the light 40 or an indication that the light 40 should bereplaced to the remote location.

The light 40 can also include another sensor, such as a motion detector,in communication with the controller 25 and/or the transmitter 44. Inthis case, the controller 25 can take signals other than the light levelsignal α into consideration in controlling the LEDs 26. For example, thecontroller 25 can turn the LEDs 26 off even though the light levelsensor 42 detects a low level of light if the motion sensor has notdetected movement for a certain amount of time. As a similar example,the controller 25 can turn the LEDs 26 off even though the light levelsensor 42 detects a low level of light if a clock or calendar incommunication with the controller 25 indicates the time is not duringstandard working hours.

The above-described embodiments have been described in order to alloweasy understanding of the invention and do not limit the invention. Onthe contrary, the invention is intended to cover various modificationsand equivalent arrangements included within the scope of the appendedclaims, which scope is to be accorded the broadest interpretation so asto encompass all such modifications and equivalent structure as ispermitted under the law.

What is claimed:
 1. An LED-based light tube for use in a conventional fluorescent fixture comprising: a housing including a light transmitting portion; at least one electrical connector attached to the housing and configured for engagement with the conventional fluorescent fixture; at least one LED arranged to produce light in a direction toward the light transmitting portion; a sensor operable to detect a brightness level and output a signal corresponding to the detected brightness level; and a controller in electrical communication with the at least one electrical connector and operable to: compare the signal to a predetermined value corresponding to a desired brightness level; and control an amount of power provided to the at least one LED in response to the signal to adjust the light produced by the at least one LED to achieve the desired brightness level.
 2. The LED-based light tube of claim 1, further comprising a circuit board disposed within the housing, and wherein the at least one LED, sensor and controller are mounted on the circuit board.
 3. The LED-based light tube of claim 1, wherein the at least one LED, the sensor and the controller are in electrical communication with the at least one electrical connector.
 4. The LED-based light tube of claim 1, wherein the at least one electrical connector includes a pair of bi-pin electrical connectors attaching to opposing ends of the housing.
 5. The LED-based light tube of claim 1, wherein the controller is operable to estimate an efficiency of the at least one LED at least partially based on the brightness level detected by the sensor.
 6. The LED-based light tube of claim 5, wherein the estimated efficiency of the at least one LED is at least partially based on a comparison of the brightness level detected by the sensor with a reference brightness level.
 7. The LED-based light tube of claim 5, wherein the controller is operable to activate an alarm when the estimated efficiency of the at least one LED is below a predetermined amount.
 8. The LED-based light tube of claim 7, wherein the alarm includes at least one of operating an LED that produces colored light, displaying the efficiency of the at least one LED on a display, and operating at the at least one LED in a flashing pattern.
 9. The LED-based light of claim 5, further comprising a transmitter operable to transmit at least one of the brightness level and the estimated efficiency of the at least one LED.
 10. A system for measuring the efficiency of a light comprising: an LED-based light including at least one electrical connector compatible with a standardized light fixture, at least one LED, and a controller in electrical communication with the at least one electrical connector and operable to control the at least one LED; and a sensor in communication with the controller and operable to detect a brightness level; wherein the controller is operable to estimate an efficiency of the at least one LED at least partially based on the brightness level detected by the sensor.
 11. The system of claim 10, wherein the controller is operable to control the at least one LED in response to the brightness level detected by the sensor.
 12. The system of claim 10, wherein the controller is operable to activate an alarm when the estimated efficiency of the at least one LED is below a predetermined value.
 13. The system of claim 10, wherein the alarm includes at least one of operating an LED that produces colored light, displaying the efficiency of the at least one LED on a display, and operating at the at least one LED in a flashing pattern.
 14. The system of claim 10, wherein the estimated efficiency of the at least one LED is at least partially based on a comparison of the brightness level detected by the sensor with a reference brightness level.
 15. The system of claim 10, wherein the at least one electrical connector includes a pair of bi-pin electrical connectors compatible with a standard fluorescent tube fixture.
 16. The system of claim 10, wherein the LED-based light further comprising a circuit board, and wherein the at least one LED, the controller and the sensor are mounted on the circuit board.
 17. The system of claim 10, wherein the sensor is remote from the LED-based light and operable to transmit a signal corresponding to the brightness level, the LED-based light further comprising a receiver in communication with the sensor and the controller.
 18. An LED-based light for use in a conventional fixture comprising: a housing including a light transmitting portion; at least one electrical connector attached to the housing and configured for engagement with the conventional fixture; at least one LED arranged to produce light in a direction toward the light transmitting portion; means for transmitting a signal corresponding to lighting information of the LED-based light; wherein the transmitted signal is usable by a remote controller to control a predetermined function separate from the LED-based light.
 19. The LED-based light of claim 18, wherein the lighting information is at least one of a brightness level or an efficiency of the LED-based light.
 20. The LED-based light of claim 18, wherein the predetermined function is at least one of a controlling a window shade or another LED-based light. 